If it does happen it will shorten my wishlist to 35L, 135L and 180L Macro.

I dont like zooms as their image quality cannot approach that of primes. This holds true if the design year are within months of each other.

Zooms are heavier than primes at the furthest focal length and max aperture.

400/5.6 with IS would be a killer light long lens.

It should sell for the same price of a 70-200/2.8 IS II.

I'd be using it at 400mm all the time so a 100-400 would be useless for me.

My sigma 10-20 at 20 is incredibly sharp as is also my 24-105 and 70-200, there is no descernable difference to my 100mm 2.8, 50 1.4 and or 400 5.6. Modern high quality zooms are excellent and produce ultra sharp images and are no way 'inferior' in image quality to primes. Unless lenses are pushing the extreme boundaries of optical performance and measured in a lab then I'm sure there will a difference but in day to day shooting, nah.

if both are true rumors (a new 100-400 and a new 400), can we expect an inner zoom on the 100-400 or the same one used on the little bro' 70-300 f/4-5.6 L IS ?

Given the reason above (shorter retracted length), I sincerely hope it's not an internal zoom, as that would likely make it even slightly longer than the 400/5.6 prime. The current 100-400 is the same size as the 70-200/2.8 and 28-300, meaning it fits nicely in a Toploader Pro 75 AW and other toploading bags. While some (like the ThinkTank ones) are expandable, I really prefer the shorter length.

Personally, I like the push-pull zooms, but I'd be ok with a rotating zoom like the 70-300L.

My sigma 10-20 at 20 is incredibly sharp as is also my 24-105 and 70-200, there is no descernable difference to my 100mm 2.8, 50 1.4 and or 400 5.6. Modern high quality zooms are excellent and produce ultra sharp images and are no way 'inferior' in image quality to primes. Unless lenses are pushing the extreme boundaries of optical performance and measured in a lab then I'm sure there will a difference but in day to day shooting, nah.

Had a Sigma, never gonna go with the brand again. This is my personal preference.

I also have a 120-300mm OS from them, and it's sharp enough, and still fares well with a 2X TC on. My only real complaint with it is the background OOF highlight circle can get very busy and this has ruined a few shots that should have been excellent - a crane fishing in a pond.

The IS also seems clumsy to activate, because often the first picture in a series is shake-blurred. Remembering to let the OS (IS) spin up before you start taking photos helps of course.

f/5.6 is fine for 800mm because you already have a narrow enough angle of view for birds. 400mm users would like to pop on a teleconverter while retaining AF.

Trying to track birds at 600mm and up is quite punishing but I find that 400mm is (even on a crop like the 7D) at or even below the bare minimum to get detail on anything but a raptor or a flock of birds. For single birds, especially small ones, I need that 600mm and a much closer minimum focus distance than 3.5M which is quite terrible actually.

The 400 F5.6 sells for $1350 in Canada. To get a longer Canon lens you have to be ready to shell out $9690. That's a HUGE jump in price.... and I'd be willing to bet that there is a market for something in between, like a 600 F5.6.

A 600mm f/5.6L would cost at least US$7,500. But a 500mm f/5.6L might come in under US$4,000.

It won't get made because they want to sell and make only 500mm f/4L lenses.

The 400 F5.6 sells for $1350 in Canada. To get a longer Canon lens you have to be ready to shell out $9690. That's a HUGE jump in price.... and I'd be willing to bet that there is a market for something in between, like a 600 F5.6.

A 600mm f/5.6L would cost at least US$7,500. But a 500mm f/5.6L might come in under US$4,000.

It won't get made because they want to sell and make only 500mm f/4L lenses.[/quote]

Very true neither Canon or Nikon are ever likely to offer a 500/5.6 or 600/5.6 with IS II even though I am sure that there is a market out there for lightweight ultra long lenses.

The best we can hope for from Canon is a new 400/5.6 with IS II and for that we would be extremely grateful - if it ever comes about!

What about Sony then? Their longest "pro" lens currently is a 300/2.8. Perhaps they may be tempted to break the stranglehold Canon/Nikon have on long lenses and come up with something tasty like a prime 500 or 600/5.6!

i would like to see both a new 100-400 and 400 is.... debating which one will be better at this stage is mute.... to me it would only make sense that they released the 400 is first, with a big improvement in IQ, then released the 100-400 6 months later with a better than current but not as good as the prime IQ... or if the prime was in fact a couple of hundred bucks cheaper!

There seem to be two DO generations - the old green ring one Canon dumped due to mediocre sharpness and horrible bokeh, and the new one they just patented for lighter tele primes which is supposed a completely other DO tech.

And I shied away and bought the 400mm f/5.6 because I was warned of internal reflections in the DO lenses. Headlights on ALMS cars for example. Could be another case of "what are you shooting"?

I have the 100 - 400 and the 400 5.6 and sold my 400mm f/2.8 (much longer tale) The 2.8 was heavy, blew in the wind and took amazing sharp and clear photos. The 100-400 for my taste is a 100-350, thus I still need a 400mm. Also the 400mm with an extender is pretty reliable, even if manual focus.

But if I'm grabbing one lens, over my shoulder and walking, for long shots, the 400mm f/5.6 is my favorite. Of course, primes are better, why not?

So maybe the DO got a bad rap and maybe they didn't quite cut it? What I really want is the 200-400mm with the 1.4x switch!

The 400 F5.6 sells for $1350 in Canada. To get a longer Canon lens you have to be ready to shell out $9690. That's a HUGE jump in price.... and I'd be willing to bet that there is a market for something in between, like a 600 F5.6.

A 600mm f/5.6L would cost at least US$7,500. But a 500mm f/5.6L might come in under US$4,000.

Pentax announced a 560mm f/5.6 for $7,000. So the $7500 price is very realistic.

What about Sony then? Their longest "pro" lens currently is a 300/2.8. Perhaps they may be tempted to break the stranglehold Canon/Nikon have on long lenses and come up with something tasty like a prime 500 or 600/5.6!